Chapter 12 -- Cell Cycle

no specfic breakdown of PMAT

cell division

reproduction of cells; leads to continuity of life; distinguishes living things

genome

all the DNA in a cell

chromosomes

packaged DNA molecules; chromatin wrapped around histones (proteins)

chromatin

eukaryotic cells; complex of DNA and proteins that condense

somatic cells

nonreproductive; 2 sets of chromosomes

gametes

reproductive

sister chromatids

each duplicated chromatid; joined copied of original

cohesins

sister chromatids attached along length by these

centromere

narrow waist of joined, duplicated sister chromatids; where they're most closely attached

mitotic (M) phase

mitosis and cytokinesis
prophase
prometaphase
metaphase
anaphase
telophase

interphase

cell growth and chromosome copying; 90% of cell cycle
G1 (first gap); growth
S (synthesis); duplication
G2 (second gap); growthm

mitotic spindle

structure made of microtubules that controls chromosome movement during mitosis

centrosome

assembly of spindle tubules begins here; microtubule organizing center

aster

radial array of short microtubules, extends from each centrosome

kinetochore

protein complex associated with centromere; each sister chromatid has

metaphase plate

imaginary plate midway between cell's 2 poles
sister chromatids line up here

seperase

cohesins created by this enzyme in anaphase

(theory of) pac-man mechanism

sister chromatids move along kinetochore microtubules to opposite cell ends during anaphase
microtubules shorten by depolymerizing at kinetochore ends
sister chromatids 'reeled in' in a way

cleavage

cytokinesis in animal cells occurs bu this process

cleavage furrow

first sign of cleavage; shallow groove in cell surface

cell plate

forms during cytokinesis for plants; made of cellulose

binary fission

how prokaryotes reproduce; origin of replication begins here (?)

cell cycle control system

sequential events of cell cycle directed by this

checkpoints

places where the cell cycle stops until 'resume' signal is received

cyclin-dependent kinases (Cdks)

protein kinases that work with maturation-promoting factors
activated by cyclins; cyclically fluctuating cell concentrations

maturation-promoting factors (MPFs)

cyclin-Cdk complex that triggers pass from G2 checkpoint --> M phase
MPF peak activity corresponds to cyclin concentration peak

G0 phase

nondividing state when G signal not received

growth factors

released by certain cells, can stimulate cell division for other cells

PDGF

growth factor; made by platelets; required for cultured fibroblast division

density-dependent inhibition

crowded cells won't divide

anchorage dependence

most animal cells show; must be attached to a substratum to divide

benign tumor

abnormal cells stay at original site; usually not harmful

malignant tumors

invade surrounding tissues; harmful

cancer cells

don't heed normal signals that regulate the cell cycle